Following the traces of some references to pre-existing matter in the Septuagint, the article analyses the interpretation of Gen 1, 2a in Philo of Alexandria’s De opificio mundi with a focus on his omission of the ἀκατασκεύαστος character of the earth. Philo’s interpretation is closely linked to his conception of emptiness and to his pioneering defence of a creation ex nihilo. In his cosmology, which is articulated as a dual interpretation of the Genesis and Plato’s Timaeus, the matter plays an (...) essential role. Philo justifies its existence on Aristotelian-Stoic grounds, highlighting the process of gradual refinement whereby matter passes from being a rough ὕλη to being an elaborate type of οὐσία. (shrink)